The commitment, to be discussed at a summit of leaders of the world's 20 biggest developing and developed economies (G20) in St. Petersburg in early September, will build on a G20 pledge made in 2010 to stabilise debt-to-GDP ratios by 2016, the official said.

Showing just how far apart different Group of 20 powers are on the issue of binding debt targets, another senior G20 source told Reuters that nothing had been committed to.

Below is a table with the numerical targets of the public debt to GDP ratios, which could be approved, according to the G20 official. The numbers for the United States and Canada are for the federal level.

The official said there were no numbers for Japan or for the bulk of emerging market economies and the targets were part of national plans of G20 members to put their public debt on a sustainable path.

The G20 source said the figures merely reflected the best guess as to future budget positions for most countries.

A meeting of G20 finance ministers and central bankers in Moscow on Friday and Saturday declined to set any debt targets, given a consensus that the shorter-term focus had to rest squarely on reviving growth.

Its final communique said progress was being made on credible medium-term fiscal strategies for the St Petersburg Summit but they should be flexible enough to support economic growth and job creation while putting debt as a share of GDP on a sustainable path.

International Monetary Fund chief Christine Lagarde told reporters after the meeting that it was up to each country to come up with the best policy mix to deliver debt reduction.

"I think the pace at which it declines ... that's this very subtle policy mix which is subject of debate between countries," she said.

"Our view is that it should be country specific, it should be progressive over time, but certainly for all of them, it should be anchored with medium-term measures, goals, that will really bring that degree of confidence that countries a serious about bringing their debt down in the long-run," she said.